Despite enormous expenditures of both financial and human resources over the last twenty-five plus years, the detection of new tumors or the recurrence of tumors remains an unfulfilled goal of humankind. Particularly frustrating is the fact that a number of cancers are treatable if detected at an early stage, but go undetected in many patients for lack of a reliable screening procedure. In addition, the need is acute for reliable screening procedures that discriminate non-metastatic primary tumors (or non-cancerous disease states) from metastatic tumors, or are predictive of progression to the metastatic state. Metastasis of tumors is a major cause of treatment failure in cancer patients. It is a complex process involving the detachment of cells from the primary neoplasm, their entrance into the circulation, and the eventual colonization of local and distant tissue sites.
Frequently, physicians must err on the side of caution, and request that a patient undergo surgical or other procedures that dramatically affects the patient's quality of life, without identification of the disease state as a tumor with a propensity to progress to the metastatic state. For illustrative purposes, two particular cancers, prostate and breast cancers, are described in more detail and are representative of cancers in need of new approaches, which the invention disclosed herein provides.
Prostate cancer is a leading cause of death in men. Thus, there is a keen interest in the etiology of this disease, as well as in the development of techniques for predicting its occurrence at early stages of oncogenesis. Little is known about the etiology of prostate cancer, the most prevalent form being adenocarcinoma. However, several studies have focused on inactivation of the tumor suppressor gene TP53 and altered DNA methylation patterns as possible factors. In addition, free radicals, arising from redox cycling of hormones, have recently been implicated in prostate cancer. This is consistent with evidence showing that the hydroxyl radical (.OH) produces mutagenic alterations in DNA, such as 8-hydroxyguanine (8-OH-Gua) and 8-hydroxyadenine (8-OH-Ade), that have been linked to carcinogenesis in a variety of studies. Despite these findings, virtually no understanding exists of the possible relationship between the .OH-modification of DNA and prostate cancer.
Prostate tissue may contain areas of benign prostatic hyperplasia (BPH), which is not regarded as a pre-malignant lesion, although it often accompanies prostate cancer. The etiology of BPH is unknown, as is its relationship to prostate cancer. Due to the difficulties in the current approaches to the diagnosis of prostate cancer, there is a need in the art for improved methods. The present invention fulfills this need, and further provides other related advantages.
Breast cancer is a leading cause of death in women and is the most common malignancy in women. The incidence for developing breast cancer is on the rise. One in nine women will be diagnosed with the disease. Standard approaches to treat breast cancer have centered around a combination of surgery, radiation and chemotherapy. In certain malignancies, these approaches have been successful and have effected a cure. However, when diagnosis is beyond a certain stage, breast cancer is most often incurable. Invasive ductal carcinoma is a common form of breast cancer which can metastasize. Alternative approaches to early detection are needed. Due to the difficulties in the current approaches to the diagnosis of breast cancer, there is a need in the art for improved methods. The present invention fulfills this need, and further provides other related advantages.
DNA is continually being modified by microenvironmental factors, thus creating vast numbers of modified structures (ref. 1,2). For example, the progression of primary breast cancer to the metastatic state was estimated to involve as many as several billion new DNA forms, many of which likely result from hydroxyl radical (.OH)-induced structural alterations (ref. 2). Progress has been made in analyzing low mass oligonucleotides (&lt;1&gt;10.sup.3 base pairs) (ref. 3). However, the complexity and high masses of the cellular DNAs (.apprxeq.6.times.10.sup.6 base pairs) have hindered their structural elucidation. Consequently, an understanding of these DNAs had to be obtained primarily by using destructive techniques (chemical or enzymatic) that provide little information on intact structures potentially having important biological properties.
The development of an infrared microscope spectrometer (FIG. 14), coupled with advanced computer software, made it possible to obtain Fourier transform-infrared (FT-IR) spectra from micrograms of cellular DNA (e.g., from biopsy specimens).